1. Technical Field
Embodiments generally relate to a media compression and, more particularly, to a method and apparatus for normalizing perceptual quality in media compression.
2. Description of the Related Art
As various forms of digital media recorders, such as digital cameras, camcorders, and voice recorders have become widely available to the public, more and more users are becoming familiar with digital media editing techniques. As technology has advanced, so has the resolution of the media capturing devices. With modern camera technology exceeding 10 megapixels in capture resolution, it is common for a single image produced in a lossless format to exceed 14 megabytes in size. These large file sizes consume large amounts of storage space, are difficult to transmit, and take additional time to load for viewing. As such, it is common for photo editing software to provide options to the user to allow for compression of the media into a smaller file format. However, compression into a smaller file format typically includes a tradeoff in media quality. In other words, the smaller the output file, the larger the loss in subjective image quality. Certain image types are more amenable to such compression than others. For example, images including text are typically more susceptible to quality loss (i.e. distortion caused by compression is more noticeable) than photographs.
While a user may currently choose a particular quality setting to which to compress a given image, the process of determining an acceptable size/quality level is fraught with trial and error. Current compression methods allow the user to specify either a target bit rate or target peak signal-to-noise ratio. Unfortunately, the subjective quality from image-to-image can vary widely even with the same bit rate or peak signal-to-noise ratio. As such, a particular setting for a given image format is not determinative for maintaining a consistent quality across multiple images in the same format. Because of the trial and error nature of this process, compressing many images at a time is difficult, if not impossible, to perform in a reasonable amount of time. As such, there is a need in the art for a method and apparatus for normalizing perceptual quality in media compression.